1. Field of the Invention
The present invention relates to a thermal spray material and to a thermal spray coated article that is provided with a thermal sprayed coating formed using this thermal spray material.
2. Description of the Related Art
The art of providing new functionalities by using various materials to coat substrate surfaces has been employed in various fields. Thermal spraying is known as one of these surface coating arts. In thermal spraying, for example, thermal sprayed particles containing a material such as a ceramic are sprayed, in a softened or melted state caused by combustion or electrical energy, onto the surface of a substrate to thereby form a thermal sprayed coating comprising the material.
In manufacturing fields, e.g., for semiconductor devices, microprocessing is commonly carried out on the surface of a semiconductor substrate by dry etching using the plasma of a halogen gas such as fluorine, chlorine, or bromine. In addition, after dry etching has been performed, the interior of the chamber (vacuum compartment) from which the semiconductor substrate has been removed is cleaned using an oxygen gas plasma. The potential for erosion thus exists here for members within the chamber that are exposed to these highly reactive oxygen gas plasmas and halogen gas plasmas. Moreover, when material eroded from a member detaches in particulate form, these particles can form foreign material (this foreign material is referred to below as particles) that attaches to the semiconductor substrate and causes circuit defects.
With the goal of reducing the generation of particles, the members exposed to plasmas, e.g., of oxygen gas plasma or halogen gas plasma, in semiconductor device fabrication equipment have been provided with ceramic thermal sprayed coatings having plasma erosion resistance. For example, WO 2014/002580 discloses that yttrium oxyfluoride can have a high plasma erosion resistance and describes the use as a thermal spray material of granules (granular particles) at least partially containing an oxyfluoride of yttrium.
However, as described in Japanese Patent No. 5,911,036, a problem was found with thermal spray materials containing yttrium oxyfluoride, i.e., during formation of the thermal sprayed coating, the fluorine becomes a gas and volatilizes, and due to this the formation of a compact thermal sprayed coating is made more difficult than when other thermal spray materials are used. Another problem was that it was difficult to control the composition of the compounds constituting the thermal sprayed coating by varying the chemical composition of the thermal spray material during thermal spraying. In addition, the increasing integration density of semiconductor devices has been accompanied by requirements for a more precise control of particle-based contamination, and a reduction in the generation of finer particles (improved dusting resistance) is thus also required of the ceramic thermal sprayed coatings disposed on semiconductor device fabrication equipment.
In view of these circumstances, an object of the present invention is to provide a thermal spray material that can form a compact thermal sprayed coating that exhibits an excellent plasma erosion resistance and an excellent dusting resistance. An additional object is to provide a thermal sprayed coating and a thermal spray coated article that are formed using this thermal spray material.